Dental caries consist of demineralization of a tooth caused by bacteria. In the early stages of caries a white spot develops on the tooth and if the disease is not halted and reversed, the enamel surface breaks down to form a lesion. This can then lead to decay and eventually, a fractured tooth. It is well known that development of dental caries may be reduced by means of various factors, such as diet and oral hygiene measures, anti-microbial treatments and the provision of fluoride to the teeth.
Tooth sensitivity is also a common problem affecting children and adults. Generally, tooth sensitivity may be caused by gingival recession, dentine exposure due to erosion or abrasion, or periodontal surgery that includes root planning. Such conditions leave the dentinal tubules of the tissue susceptible to irritation by chemical, bacterial, mechanical or thermal stimuli. Examples of stimuli include heat, cold, and sweet foods. It is believed that tooth sensitivity is the result of nerve endings of the dental pulp being excited by fluid flow through the exposed dentinal tubules.
Treatments directed to alleviating pain associated with sensitive teeth have generally focused on blocking access to the dentinal tubules so as to prevent stimuli from causing pain and sensitivity. Many treatments have been developed which include application of inorganic or organic components designed to plug or otherwise block dentinal tubules for a limited time. A disadvantage of such treatments is that normal habits such as eating certain foods (e.g., foods with a high acid content) or brushing can negate the treatment. Recently, testing has revealed that increased fluoride levels within the mouth may also be used as a treatment for tooth sensitivity Toumba and Andreadis).
Current methods for administering fluoride for caries prevention include the fluoridation of drinking water, the ingestion of fluoride tablets, the incorporation of fluoride into mouth washes, toothpastes, and foods, the topical application of fluoride solutions, gels and varnishes and recently, the incorporation of fluoride in dental materials and devices.
Evidence supports the concept of frequent applications of relatively low concentrations of fluoride ions for the prevention of caries and the treatment of sensitive teeth. A sustained and controlled release delivery system could help to achieve this goal.
Arginine and other basic amino acids have been proposed for use in oral care and are believed to have significant benefits in combating cavity formation and tooth sensitivity. Combining these basic amino acids with minerals having oral care benefits, e.g., fluoride and calcium, to form an oral care product having acceptable long term stability, however, has proven challenging. Partly because of unaddressed formulation hurdles and partly because arginine has generally been viewed in the art as a potential alternative to fluoride rather than a co-active, there has been little motivation to make oral care products comprising both arginine and fluoride. Additional hurdles are potentially posed by addition of an antimicrobial agent. Commercially available arginine-based toothpaste, such as ProClude® and DenClude®, for example, contain arginine bicarbonate and calcium carbonate, but not fluoride nor any antimicrobial agent.